Additionally, some network settings in the registry are reverted to their default values unexpectedly.

This problem occurs if you have applied some TCP-acceleration (TCP-A) and network direct memory access (NetDMA) settings before the upgrade.

CAUSE

A fix that is included in Windows Server 2008 R2 has a defect. This defect prevents certain additional settings from being updated during upgrade. Therefore, after the upgrade fails, the system restores some settings to their default values.

WORKAROUND

To work around this problem, remove the following settings if you have applied them, and then upgrade to Windows Server 2008 R2:

Subkey:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters

Entry:

EnableTcpa

Subkey:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters

Entry:

EnableDca

After you upgrade to Windows Server 2008 R2, reapply these settings.

MORE INFORMATION

When this problem occurs, the following settings are restored to the default values: